Sertraline hydrochloride is a known compound having the following structural formula:

Sertraline, in the form of its hydrochloride salt, is the active principle of the medicinal product known under the trademark Zoloft®, useful in the treatment of depression, obsessive-compulsive disorders, panic disorders and premature ejaculation.
Sertraline hydrochloride can exist in different crystalline forms which differ from each other in terms of stability, physical properties, spectral data and methods of preparation.
U.S. Pat. No. 4,536,518 (Pfizer Inc.) describes a synthesis of sertraline hydrochloride by treating an ethyl acetate/ether solution of free base with gaseous hydrogen chloride. This patent does not refer to specific polymorphic crystalline forms of sertraline hydrochloride.
U.S. Pat. No. 5,248,699 (Pfizer Inc.) discloses 5 polymorphic forms of sertraline hydrochloride (I, II, III, IV and V), which can be characterized by single crystal x-ray analysis, powder x-ray diffraction, infra-red spectroscopy and differential scanning calorimetry.
According to U.S. Pat. No. 5,248,699, sertraline hydrochloride produced by the method of U.S. Pat. No. 4,536,518 has a crystalline form corresponding to form II.
U.S. Pat. No. 5,734,083 (Torcan Chemical Ltd.) discloses another polymorphic form of sertraline hydrochloride (=T 1), and the process of preparation thereof.
U.S. Pat. No. 6,500,987 (Teva Pharm. Ind.) describes processes for making sertraline hydrochloride form II, III IV and V and mentions further crystalline forms of sertraline hydrochloride, such as form VI (solvated crystal form with methanol or ethanol), forms VII–IX (different hydrate forms) and form X (solvated crystal form with benzyl alcohol)
Sertraline hydrochloride is usually prepared by acidification of a solution of sertraline base or a salt thereof with hydrogen chloride (both gaseous hydrogen chloride and aqueous hydrogen chloride).
The preparation of sertraline hydrochloride by addition of aqueous hydrochloric acid is a straight process but it is characterized by lower yields due to solubility of sertraline hydrochloride in water.
The alternative use of gaseous hydrogen chloride on a large scale would give rise to high equipment costs and typical risks of gas handling.